I have some 6-7 foot purple Cosmos that look exactly like the baby brothers of yours from these posts:
May 16, 2010 3:12 AM
Sep 28, 2010 2:52 PM
(also seedling pics)
Mine also came from a trade (from sunngrrl or sunnygirl) and were called
"Cosmos Dazzler"
Cosmos bipinnatus
scarlet (deep pink)
[A] self-sows freely
2-4' tall.
Most of mine are a pale purple (lavender?) but around 1/3 - 1/4 are deeper purple.
I started them in trays indoors, and they did nothing for weeks after going outdoors. Then, for months, they just just bushy and tall.
They didn't bloom until it started getting cold, and now they are profuse!
But if I cut them and bring them indoors, they fade and drop in 1-2 days.
Corey